JP6160105B2 - Pulverized coal burner - Google Patents

Description

  The present invention relates to a pulverized coal burner that is provided on the wall of a boiler furnace and burns pulverized coal, and more particularly to a pulverized coal burner having a plasma torch for pulverized coal ignition.

  Some pulverized coal burners use a plasma torch for ignition of pulverized coal. The plasma torch generates high-temperature plasma, so it can be easily applied to pulverized coal with a low volatile content. By using a plasma torch, the fuel supply system does not require an oil supply system, and pulverized coal can be supplied. One system can be used, and the equipment can be simplified. In addition, since the plasma is high temperature, it is possible to start in a state where the furnace is cold, that is, to start a cold can.

  However, when a plasma torch is used as the ignition means, there is a problem in the stability of ignition and the stability of the flame formed because the high temperature region formed by the plasma is narrow.

  In Patent Document 1, a plasma torch is incorporated in the center of a pulverized coal combustion burner having a burner tile, pulverized coal and primary air are blown into the high temperature portion of the plasma jet, and secondary air is swirled so as to surround the plasma jet. A burner for a plasma assisted combustion furnace that completely burns pulverized coal by supplying the pulverized coal is disclosed.

JP-A-6-265109

  In view of such circumstances, the present invention provides a pulverized coal burner that improves the stability of ignition at start-up and the stability of flames formed in a normal furnace.

  The present invention includes an outer cylinder nozzle that opens toward the furnace and ejects while swirling a pulverized coal mixed flow in which pulverized coal and conveying air are mixed, and is concentric with the outer cylinder nozzle inside the outer cylinder nozzle. A nozzle main body having an inner cylinder nozzle for ejecting auxiliary combustion air, a secondary air adjusting device for ejecting combustion air from the periphery of the nozzle main body, and a plasma torch for ejecting plasma, According to the pulverized coal burner in which the plasma torch is disposed so that a staying part for increasing the pulverized coal concentration is formed on the inner surface of the outer cylinder nozzle, and plasma is ejected to the pulverized coal mixed flow ejected from the staying part. Is.

  The present invention further includes a plurality of deflector angles provided along the axial direction provided on the inner surface of the outer cylinder nozzle, and the deflector angles projecting in the axial direction from the other deflector angles. A staying part forming member is formed, and the staying part relates to a pulverized coal burner formed by the staying part forming member.

  The present invention further includes a groove formed on the inner surface of the outer cylinder nozzle adjacent to the staying portion forming member, wherein the staying portion is a fine powder formed by the staying portion forming member and the groove. It concerns charcoal burners.

  The present invention further includes a concave groove formed on the inner surface of the outer cylinder nozzle, and the retention portion relates to a pulverized coal burner formed by the concave groove.

  Furthermore, the present invention relates to a pulverized coal burner in which a plurality of the stay portions are formed at equal circumferential intervals.

  According to the present invention, an outer cylinder nozzle that opens toward the furnace and jets while swirling a pulverized coal mixed flow in which pulverized coal and conveying air are mixed, and the outer cylinder nozzle inside the outer cylinder nozzle A nozzle body having an inner cylinder nozzle that is concentrically provided and ejects auxiliary combustion air, a secondary air adjustment device that ejects combustion air from the periphery of the nozzle body, and a plasma torch that ejects plasma The plasma torch is disposed so that a staying portion for increasing the pulverized coal concentration is formed on the inner surface of the outer cylinder nozzle, and plasma is ejected to the pulverized coal mixed flow ejected from the staying portion. Ignition stability is improved by passing a high-concentration pulverized coal mixed flow through a high temperature region formed by the above, and stable ignitability of pulverized coal can be obtained even when the furnace temperature is low. Along with the fire Temperature is exhibited an excellent effect that it is possible to improve the stability of the flame formed on 該火 furnaces In the normal increase.

1 is a schematic vertical sectional view showing a pulverized coal burner according to a first embodiment of the present invention. (A) is explanatory drawing which shows the structure of the outer cylinder nozzle which concerns on 1st Example of this invention, and its periphery part, (B) is the outer cylinder nozzle which shows the modification of 1st Example of this invention. It is explanatory drawing of a structure of the periphery part. It is a schematic elevation sectional drawing which shows the pulverized coal burner which concerns on the 2nd Example of this invention. (A) is explanatory drawing which shows the structure of the outer cylinder nozzle which concerns on the 2nd Example of this invention, and its periphery part, (B) is the outer cylinder nozzle which shows the modification of the 2nd Example of this invention. It is explanatory drawing of a structure of the periphery part. (A) is explanatory drawing which shows the structure of the outer cylinder nozzle which concerns on the 3rd Example of this invention, and its peripheral part, (B) is the outer cylinder nozzle which shows the modification of the 3rd Example of this invention. It is explanatory drawing of a structure of the periphery part.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, with reference to FIG. 1 and FIG. 2 (A), the pulverized coal burner 1 according to the first embodiment of the present invention will be described.

  In FIG. 1, 2 is a furnace of a boiler (not shown), and 3 is a furnace wall of the furnace 2. A throat 4 is provided on the furnace wall 3, a wind box 5 is attached to the counter-fire furnace 2 side of the furnace wall 3, and the pulverized coal burner 1 is provided concentrically with the throat 4 inside the wind box 5. Yes.

  The pulverized coal burner 1 has a nozzle body 6 on the center axis of the pulverized coal burner 1, is connected to the throat 4, and is provided so as to surround the tip of the nozzle body 6. A secondary air conditioner 7 concentric with the main body 6 is provided.

  The nozzle body 6 includes an outer cylinder nozzle 8 and an inner cylinder nozzle 9 provided concentrically with the outer cylinder nozzle 8, and between the outer cylinder nozzle 8 and the inner cylinder nozzle 9, A fuel-conducting space 11 having an open end at the furnace 2 side is formed in a hollow cylindrical space.

  On the inner peripheral surface of the outer cylinder nozzle 8, deflector angles 12 having a triangular shape in cross section are disposed at a predetermined number of pitches in the circumferential direction at a predetermined angle pitch, for example, 45 ° intervals. Yes. Further, one of the deflector angles 12 is a stay portion forming member 13 that protrudes toward the axis of the outer cylinder nozzle 8 higher than the other deflector angles 12. The staying portion forming member 13 does not need to be high over the entire length, and only the tip portion needs to be high. The length of the tip in the axial direction is a predetermined length from the tip, for example, a length sufficient to form a staying portion 16 described later.

  A pulverized coal mixed flow introduction pipe 14 communicates with the base of the outer cylinder nozzle 8 (the end on the side of the counter-fired furnace 2) from the tangential direction. The pulverized coal mixed flow introduction pipe 14 is connected to a pulverized coal mill (not shown), and the pulverized coal mixed flow introduction pipe 14 is mixed with primary air, which is conveying air, and pulverized coal. The charcoal mixed flow 15 flows into the fuel conduction space 11 from the tangential direction.

  The pulverized coal mixed flow 15 flows toward the front end side while turning inside the fuel conduction space 11. The pulverized coal mixed flow 15 is ejected from the tip of the outer cylinder nozzle 8 (the furnace 2 side end) while forming the stagnation part 16 in which the pulverized coal concentration is increased by the stagnation part forming member 13 in the course of flow. It is supposed to be done.

  Further, a plasma torch 17 is provided outside the outer cylinder nozzle 8 so as to penetrate the window box 5. The plasma torch 17 is inclined so as to gradually approach the outer cylinder nozzle 8 toward the tip, and the tip of the plasma torch 17 is located in the vicinity of the tip of the staying portion 16.

  A secondary air blowing duct 18 communicates with the wind box 5, and secondary air 19, which is combustion air, flows into the wind box 5 through the secondary air blowing duct 18.

  One end of the tertiary air introduction pipe 21 communicates with the base of the inner cylinder nozzle 9, and the other end opens inside the wind box 5. The tertiary air introduction pipe 21 is provided with a tertiary air flow rate adjustment valve 22. The tertiary air introduction pipe 21 takes in a part of the secondary air 19 from the window box 5, adjusts the flow rate by the tertiary air flow rate adjustment valve 22, and forms the tertiary air 23 as auxiliary combustion air. It leads into the inner cylinder nozzle 9.

  The secondary air adjusting device 7 includes an auxiliary air adjusting mechanism 24 that houses the tip of the nozzle body 6, and a main air adjusting mechanism 25 that is provided concentrically outside the auxiliary air adjusting mechanism 24. Yes.

  The auxiliary air adjustment mechanism 24 includes a first air guide duct 26 that is reduced in diameter toward the tip, and a large number of inner air vanes 27 that are rotatably provided at equal circumferential intervals. Can be rotated synchronously via a link mechanism (not shown), and the inclination angle with respect to the air flow can be changed. The main air adjustment mechanism 25 includes a second air guide duct 28 that is reduced in diameter toward the tip, and a plurality of outer air vanes 29 that are rotatably provided at equal circumferential intervals. Like the inner air vane 27, the vane 29 can be rotated synchronously via a link mechanism (not shown), and the inclination angle with respect to the air flow can be changed.

  The tip of the second air guide duct 28 is continuous with the throat 4, and the tip of the first air guide duct 26 is at a position retracted from the inner wall surface of the furnace wall 3. The tip of the inner cylinder nozzle 9 is also at a position retracted from the inner wall surface of the furnace wall 3.

  Next, combustion in the pulverized coal burner 1 will be described.

  The pulverized coal pulverized by a pulverized coal mill (not shown) is conveyed by primary air, and is supplied as a pulverized coal mixed flow 15 to the base of the fuel conduction space 11 from the pulverized coal mixed flow introduction pipe 14. The charcoal mixed stream 15 flows toward the furnace 2 while turning in the fuel conduction space 11.

  In the course of flowing through the fuel conduction space 11, the pulverized coal mixed flow 15 is made uniform by the deflector angle 12 so that the concentration of the pulverized coal in the pulverized coal mixed flow 15 is suppressed, and swirling is suppressed. The pulverized coal mixed stream 15 swirled by the staying part forming member 13 is blocked by the stagnation part forming member 13 and part of the pulverized coal mixed stream 15 stays adjacent to the staying part forming member 13. The staying portion 16 having an increased pulverized coal concentration is formed.

  When the pulverized coal mixed flow 15 is ejected from the tip of the outer cylinder nozzle 8, the high-concentration pulverized coal mixed flow in which the plasma ejected from the plasma torch 17 is ejected from the tip of the staying portion 16. 15 and pulverized coal is ignited.

  Further, the secondary air 19 as combustion air is supplied to the window box 5, and the secondary air 19 is adjusted in turning force or turning force and air volume by the outer air vane 29. 2 is sent to the throat 4 through the air guide duct 28.

  A part of the secondary air 19 taken into the second air guide duct 28 is taken into the first air guide duct 26 via the inner air vane 27 and used for secondary auxiliary combustion. Spouted as air. The inner air vane 27 is inclined with respect to the air flow, and adjusts the turning force or the turning force and the air volume of a part of the taken-in secondary air 19.

  Adjustment of the turning force and air volume by the outer air vane 29 and adjustment of the turning force and air volume by the inner air vane 27 change the supply amount and flow state of the secondary air 19 to adjust the combustion state of pulverized coal. The

  A part of the secondary air 19 is taken in as tertiary air 23 through the tertiary air introduction pipe 21. The tertiary air 23 flows through the inner cylinder nozzle 9 and is ejected from the tip of the inner cylinder nozzle 9 to the throat 4.

  The combustion state of pulverized coal is adjusted by ejecting the tertiary air 23. Therefore, the combustion state of the pulverized coal is adjusted to be optimum by adjusting the secondary air 19 and the tertiary air 23.

  As described above, in the first embodiment, one of the deflector angles 12 is protruded toward the axis of the outer cylinder nozzle 8 to form the staying part forming member 13, and the staying part forming member 13. The pulverized coal mixed stream 15 is retained by the above-described method to form the stagnation part 16 in which the pulverized coal concentration is increased, and the plasma so as to intersect with the high concentration pulverized coal mixed stream 15 ejected from the stagnation part 16. Plasma is emitted from the torch 17 and ignited.

  Therefore, a large amount of pulverized coal (high-concentration pulverized coal mixed flow) passes through the high-temperature region formed by the plasma, so that the ignition stability of the pulverized coal is improved, and when the boiler having a low temperature of the furnace 2 is started ( Even when the can is started), stable ignitability of the pulverized coal can be obtained because of the high temperature of the plasma, and in the normal time when the temperature of the furnace 2 rises, The stability of the flame formed can be improved.

  FIG. 2B shows a modification of the pulverized coal burner 1 in the first embodiment. In the modification in the first embodiment, the staying portion forming members 13 are formed at a plurality of, for example, four locations at equal circumferential intervals.

  In the above modification, the staying portions 16 are formed at four places. However, the staying portions 16 are also formed at equal circumferential intervals similarly to the staying portion forming member 13, so that the pulverized coal that turns A stable swirl flow can be obtained without causing the mixed flow 15 to flow unevenly.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4A. 3 and 4A, the same components as those in FIGS. 1 and 2A are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, one of the deflector angles 12 provided on the inner surface of the outer cylinder nozzle 8 is removed, and a predetermined axial direction from the tip is provided at the place where the removed deflector angle 12 is provided. For example, a groove 31 having a length sufficient to form the staying portion 16 is formed.

  The tip of the plasma torch 17 that passes through the window box 5 and gradually approaches the outer cylinder nozzle 8 toward the tip is located in the vicinity of the tip of the concave groove 31.

  In the second embodiment, in the process in which the pulverized coal mixed flow 15 flows through the fuel conduction space 11, the pulverized coal concentration in the pulverized coal mixed flow 15 is made uniform by the deflector angle 12, and swirling is suppressed. Thus, a speed in the axial direction is given, and the swirling pulverized coal mixed flow 15 flows into the concave groove 31, so that a part of the pulverized coal mixed flow 15 stays in the concave groove 31. In the concave groove 31, the staying portion 16 having an increased pulverized coal concentration is formed.

  When the pulverized coal mixed flow 15 is ejected from the tip of the outer cylinder nozzle 8, the plasma ejected from the plasma torch 17 is mixed with the pulverized coal with high concentration ejected from the tip of the concave groove 31. Crosses stream 15 and pulverized coal is ignited.

  As described above, in the second embodiment, one of the deflector angles 12 is removed, and the concave groove 31 is formed at a position where the deflector angle 12 is provided. The plasma 16 is ejected from the plasma torch 17 and ignited so as to intersect the high-concentration pulverized coal mixed flow 15 ejected from the residence part 16.

  Accordingly, a large amount of pulverized coal (mixed flow of high-concentration pulverized coal) passes through the high-temperature region formed by the plasma, so that the ignition stability of the pulverized coal is improved and the temperature of the furnace 2 (see FIG. 1) is low. Even at the time of starting (at the time of starting the cold can), since the plasma is high temperature, stable ignitability of pulverized coal can be obtained, and at the normal time when the temperature of the furnace 2 is increased, The stability of the flame formed in the furnace 2 can be improved.

  FIG. 4B shows a modification of the pulverized coal burner 1 in the second embodiment. In the modification in the second embodiment, the concave grooves 31 are formed at a plurality of, for example, four locations at equal circumferential intervals.

  In the above modification, the staying portion 16 is also formed at equal circumferential intervals similarly to the concave groove 31, so that a stable swirling flow can be achieved without causing a drift in the flow of the swirling pulverized coal mixed flow 15. can do.

  Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 5A, the same components as those in FIGS. 1 and 2A are denoted by the same reference numerals, and the description thereof is omitted.

  The third embodiment is a combination of the first embodiment and the second embodiment, and one of the deflector angles 12 is connected to the shaft of the outer cylinder nozzle 8 more than the other deflector angles 12. A stagnant portion forming member 32 projecting toward the center is made high, and a groove is formed in the inner surface of the outer cylinder nozzle 8 adjacent to the counter-rotating side of the pulverized coal mixed flow 15 of the stagnant portion forming member 32. 33 is formed. The staying part forming member 32 and the recessed groove 33 are assumed to have a length sufficient to form the staying part 16 together.

  The tip of the plasma torch 17 that passes through the window box 5 and gradually approaches the outer cylinder nozzle 8 toward the tip is located in the vicinity of the tip of the concave groove 33.

  Also in the third embodiment, in the process in which the pulverized coal mixed flow 15 flows in the fuel conduction space 11, the pulverized coal concentration in the pulverized coal mixed flow 15 is made uniform by the deflector angle 12, and swirling is performed. Suppressed and given a speed in the axial direction. Further, the swirling pulverized coal mixed flow 15 flows into the concave groove 33 and is dammed by the staying portion forming member 32, whereby a part of the pulverized coal mixed flow 15 stays and the concave groove The staying portion 16 having an increased pulverized coal concentration is formed in the portion 33 and adjacent to the staying portion forming member 32.

  When the pulverized coal mixed stream 15 is ejected from the tip of the outer cylinder nozzle 8, the plasma ejected from the plasma torch 17 is the high concentration pulverized coal mixed stream 15 ejected from the staying portion 16. And pulverized coal is ignited.

  Also in the third embodiment, a large amount of pulverized coal (mixed flow of high-concentration pulverized coal) passes through a high-temperature region formed by plasma, as in the first and second embodiments. Therefore, the ignition stability of the pulverized coal is improved, and the pulverized coal is stable because the plasma is at a high temperature even when the boiler 2 (see FIG. 1) is started at a low temperature (when the can is started). In addition to obtaining ignitability, it is possible to improve the stability of the flame formed in the furnace 2 even when the temperature of the furnace 2 is increased.

  FIG. 5B shows a modification of the pulverized coal burner 1 in the third embodiment. In the modified example of the third embodiment, the staying portion forming member 32 and the concave groove 33 are formed at a plurality of, for example, four locations at equal circumferential intervals.

  In the above modification, the staying portion 16 is also formed at equal circumferential intervals like the staying portion forming member 32 and the recessed groove 33, so that the flow of the swirling pulverized coal mixed flow 15 is drifted. And a stable swirl flow.

  Further, in the first to third embodiments, the pulverized coal can be stably ignited even when the boiler 2 has a low temperature at the start of the boiler (at the start of the cold can). Therefore, an oil burner or the like for raising the temperature of the furnace 2 at the time of starting the boiler becomes unnecessary, and it is possible to reduce the manufacturing cost and the fuel cost.

  In the first to third embodiments, the case where the plasma torch 17 is used as the igniting means of pulverized coal has been described. However, when means other than plasma are used as the igniting means, or brown coal Even in the case of burning low-grade coal such as the above, by forming the staying portion 16 and creating a region where the pulverized coal concentration is increased, the ignition stability is improved and the flame formed in the furnace 2 is reduced. Stability can be improved.

  In the first to third embodiments, the plasma torch 17 is provided through the window box 5 around the outer cylinder nozzle 8, but the plasma torch 17 is a plasma. The pulverized coal mixed flow 15 whose concentration has been increased in the stay portion 16 may be provided so as to pass through, for example, the inner tube nozzle 9 in the state where the plasma torch 17 is inclined. It may be inserted through.

DESCRIPTION OF SYMBOLS 1 Pulverized coal burner 2 Furnace 6 Nozzle body 7 Secondary air conditioner 8 Outer cylinder nozzle 9 Inner cylinder nozzle 11 Fuel conduction space 12 Deflector angle 13 Retention part forming member 15 Pulverized coal mixed flow 16 Retention part 17 Plasma torch 19 Secondary air 23 Tertiary air 31 Groove 32 Retention part forming member 33 Groove

Claims (4)

An outer cylinder nozzle that opens toward the furnace and spouts while swirling a pulverized coal mixed flow in which pulverized coal and transport air are mixed, and an auxiliary cylinder nozzle that is provided concentrically with the outer cylinder nozzle inside the outer cylinder nozzle A nozzle body having an inner cylinder nozzle that ejects combustion air; a secondary air conditioner that ejects combustion air from around the nozzle body; a plasma torch that ejects plasma; and an inner surface of the outer cylinder nozzle A plurality of deflector angles extending along the axial direction provided, and a staying portion forming member is formed by the deflector angle projecting in the axial direction from the other deflector angles, and the staying portion formation the retention portion to increase the pulverized coal concentration at the tip portion of the inner surface of the outer tube nozzle formed by members, the plasma such that plasma in the pulverized coal mixture flow ejected from該滞engaging portion is ejected Pulverized coal burner, characterized in that the torch is disposed. 2. The pulverized coal according to claim 1 , further comprising a recessed groove formed on an inner surface of the outer cylinder nozzle adjacent to the staying part forming member, wherein the staying part is formed by the staying part forming member and the recessed groove. Burner. An outer cylinder nozzle that opens toward the furnace and spouts while swirling a pulverized coal mixed flow in which pulverized coal and transport air are mixed, and an auxiliary cylinder nozzle that is provided concentrically with the outer cylinder nozzle inside the outer cylinder nozzle A nozzle body having an inner cylinder nozzle that ejects combustion air; a secondary air conditioner that ejects combustion air from around the nozzle body; a plasma torch that ejects plasma; and an inner surface of the outer cylinder nozzle And forming a staying portion for increasing the pulverized coal concentration at the tip of the inner surface of the outer cylinder nozzle by the groove , and plasma in the pulverized coal mixed flow ejected from the staying portion. A pulverized coal burner, characterized in that the plasma torch is disposed so as to erupt. The pulverized coal burner according to any one of claims 1 to 3 , wherein a plurality of the stay portions are formed at equal circumferential intervals.

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